Effects of vision therapy on near exodeviation in children with convergence insufficiency treated during the convergence insufficiency treatment trials.

PURPOSE: To report the change in the magnitude of near exodeviation in children with symptomatic convergence insufficiency successfully treated with office-based vergence/accommodative therapy in the Convergence Insufficiency Treatment Trial-Attention and Reading Trial. METHODS: A total of 131 children 9-14 years of age with symptomatic convergence insufficiency classified as successfully treated with office-based vergence/accommodative therapy at the 16-week outcome visit were included. Masked examiners measured the near ocular deviation by the prism and alternate cover test at baseline, primary outcome and 1-year post-treatment. The mean change in near deviation was calculated from baseline to primary outcome, from primary outcome to 1-year post-treatment and from baseline to 1-year post-treatment. RESULTS: Of the 131 participants successfully treated with vergence/accommodative therapy, 120 completed the 1-year post-treatment visit. A significant change in near exodeviation was observed at baseline to primary outcome (2.6Δ less exo, p < 0.001, moderate effect size d = 0.61) and at baseline to 1-year post-treatment (2.0Δ less exo; p < 0.001, small effect size d = 0.45). The change from primary outcome to 1-year post-treatment (0.6Δ more exo; p = 0.06, small effect size d = 0.11) was not significant. Forty per cent (48/120) of participants had a decrease in near exodeviation >3.5∆ (expected test/retest variability) between baseline and the primary outcome examination. Of the 120 participants, one (1.0%) was esophoric at the primary outcome and was subsequently exophoric at 1-year post-treatment. Four participants (3.3%) who were orthophoric or exophoric at the primary outcome were esophoric (all ≤3∆) at the 1-year post-treatment visit. CONCLUSION: On average, the near exodeviation was smaller in size immediately after the discontinuation of vergence/accommodative therapy (2.6∆, moderate effect size) and 1 year post vergence/accommodative therapy (2.0∆, small effect size) in children with convergence insufficiency who were successfully treated; 40% had a clinically meaningful decrease in exophoria. The development of near esophoria was rare.

Neural consequences of symptomatic convergence insufficiency: A small sample study.

INTRODUCTION: Convergence insufficiency (CI) is an oculomotor abnormality characterised by exophoria and inadequate convergence when focusing on nearby objects. CI has been shown to cause symptoms when reading. However, the downstream consequences on brain structure have yet to be investigated. Here, we investigated the neural consequences of symptomatic CI, focusing on the left arcuate fasciculus, a bundle of white matter fibres which supports reading ability and has been associated with reading deficits. METHODS: We compared the arcuate fasciculus microstructure of participants with symptomatic CI versus normal binocular vision (NBV). Six CI participants and seven NBV controls were included in the analysis. All participants were scanned with 3 T magnetic resonance imaging (MRI), and anatomical and diffusion-weighted images were acquired. Diffusion-weighted images were processed with TRACULA to identify the arcuate fasciculus in each participant and compute volume and radial diffusivity (RD). RESULTS: Compared with NBV controls, those with symptomatic CI had significantly smaller arcuate fasciculi bilaterally (left: t = -3.21, p = 0.008; right: t = -3.29, p = 0.007), and lower RD in the left (t = -2.66, p = 0.02), but not the right (t = -0.81, p = 0.44, false discovery rate (FDR)-corrected p > 0.05) arcuate fasciculus. Those with higher levels of reading symptoms had smaller arcuate fasciculi (r = -0.74, p = 0.004) with lower RD (r = -0.61, p = 0.03). CONCLUSIONS: These findings suggest that symptomatic CI may lead to microstructural changes in the arcuate fasciculus. Since it is highly unlikely that abnormalities in the arcuate fasciculus are the cause of the neuromuscular deficits in the eyes, we argue that these changes may be a potential neuroplastic consequence of disruptions in sustained reading.

Detection of significant vision conditions in children using QuickSee wavefront autorefractor.

PURPOSE: This study evaluated the ability of QuickSee to detect children at risk for significant vision conditions (significant refractive error [RE], amblyopia and strabismus). METHODS: Non-cycloplegic refraction (using QuickSee without and with +2 dioptre (D) fogging lenses) and unaided binocular near visual acuity (VA) were measured in 4- to 12-year-old children. Eye examination findings (VA, cover testing and cycloplegic retinoscopy) were used to determine the presence of vision conditions. QuickSee performance was summarised by area under the receiver operating characteristic curve (AUC), sensitivity and specificity for various levels of RE. QuickSee referral criteria for each vision condition were chosen to maximise sensitivity at a specificity of approximately 85%-90%. Sensitivity and specificity to detect vision conditions were calculated using multiple criteria. Logistic regression was used to evaluate the benefit of adding near VA (6/12 or worse) for detecting hyperopia. A paired t-test compared QuickSee without and with fogging lenses. RESULTS: The mean age was 8.2 (±2.5) years (n = 174). RE ranged up to 9.25 D myopia, 8 D hyperopia, 5.25 D astigmatism and 3.5 D anisometropia. The testability of the QuickSee was 94.3%. AUC was ≥0.92 (excellent) for each level of RE. For the detection of any RE, sensitivity and specificity were 84.2% and 87.3%, respectively, using modified Orinda criteria and 94.5% and 78.2%, respectively, using the American Academy for Pediatric Ophthalmology and Strabismus (AAPOS) guidelines. For the detection of any significant vision condition, the sensitivity and specificity of QuickSee were 81.1% and 87.9%, respectively, using modified Orinda criteria and 93% and 78.6%, respectively, using AAPOS criteria. There was no significant benefit of adding near VA to QuickSee for the detection of hyperopia ≥+2.00 (p = 0.34). There was no significant difference between QuickSee measurements of hyperopic refractive error with and without fogging lenses (difference = -0.09 D; p = 0.51). CONCLUSIONS: QuickSee had high discriminatory power for detecting children with hyperopia, myopia, astigmatism, anisometropia, any significant refractive error or any significant vision condition.

Impact of accommodative insufficiency and accommodative/vergence therapy on ciliary muscle thickness in the eye.

PURPOSE: Recent evidence suggests that the ciliary muscle apical fibres are most responsive to accommodative load; however, the structure of the ciliary muscle in individuals with accommodative insufficiency is unknown. This study examined ciliary muscle structure in individuals with accommodative insufficiency (AI). We also determined the response of the ciliary muscle to accommodative/vergence therapy and increasing accommodative demands to investigate the muscle's responsiveness to workload. METHODS: Subjects with AI were enrolled and matched by age and refractive error with subjects enrolled in another ciliary muscle study as controls. Anterior segment optical coherence tomography was used to measure the ciliary muscle thickness (CMT) at rest (0D), maximum thickness (CMTMAX) and over the area from 0.75 mm (CMT0.75) to 3 mm (CMT3) posterior to the scleral spur of the right eye. For those with AI, the ciliary muscle was also measured at increasing levels of accommodative demand (2D, 4D and 6D), both before and after accommodative/vergence therapy. RESULTS: Sixteen subjects with AI (mean age = 17.4 years, SD = 8.0) were matched with 48 controls (mean age = 17.8 years, SD = 8.2). On average, the controls had 52-72 µm thicker ciliary muscles in the apical region at 0D than those with AI (p = 0.03 for both CMTMAX and CMT 0.75). Differences in thickness between the groups in other regions of the muscle were not statistically significant. After 8 weeks of accommodative/vergence therapy, the CMT increased by an average of 22-42 µm (p ≤ 0.04 for all), while AA increased by 7D (p < 0.001). CONCLUSIONS: This study demonstrated significantly thinner apical ciliary muscle thickness in those with AI and that the ciliary muscle can thicken in response to increased workload. This may explain the mechanism for improvement in signs and symptoms with accommodative/vergence therapy.

Functional magnetic resonance imaging activation for different vergence eye movement subtypes.

INTRODUCTION: Maddox suggested that there were four convergence subtypes, each driven by a different stimulus. The purpose of this study was to assess the neural correlates for accommodative convergence, proximal convergence (convergence stimulus provided), disparity convergence and voluntary convergence (no specific convergence stimulus provided) using functional magnetic resonance imaging (fMRI). METHODS: Ten subjects (mean age = 24.4 years) with normal binocular vision participated. The blood oxygenation level-dependent (BOLD) signals of the brain from fMRI scans were measured when subjects made vergence eye movements while: (1) alternately viewing letters monocularly where one eye viewed through a -2.00 D lens, (2) alternately viewing Difference of Gaussian targets monocularly at distance and near, (3) viewing random dot stereograms with increasing disparity and (4) voluntarily converging the eyes with binocular viewing. RESULTS: The accommodative convergence paradigm resulted in activation on the right side in the right fusiform cortex and the right middle occipital cortex. The proximal convergence stimulus mainly activated areas in the right occipital lobe. The disparity stimulus activated areas in the left occipital cortex and the left frontal cortex. Finally, the voluntary convergence paradigm resulted in activation primarily in the occipital lobe and mostly bilaterally. CONCLUSION: The accommodative, proximal, disparity and voluntary convergence paradigms resulted in activation in unique areas in the brain with functional MRI. Activation was found in more areas in the proximal and voluntary conditions compared with the accommodative and disparity conditions.

Does coexisting accommodative dysfunction impact clinical convergence measures, symptoms and treatment success for symptomatic convergence insufficiency in children?

PURPOSE: To determine whether coexisting accommodative dysfunction in children with symptomatic convergence insufficiency (CI) impacts presenting clinical convergence measures, symptoms and treatment success for CI. METHODS: Secondary data analyses of monocular accommodative amplitude (AA; push-up method), monocular accommodative facility (AF; ±2.00 D lens flippers) and symptoms (CI Symptom Survey [CISS]) in children with symptomatic CI from the Convergence Insufficiency Treatment Trial (N = 218) and CITT-Attention and Reading Trial (N = 302) were conducted. Decreased AA was defined as more than 2D below the minimum expected amplitude for age (15 - » age); those with AA < 5 D were excluded. Decreased AF was defined as <6 cycles per minute. Mean near point of convergence (NPC), near positive fusional vergence (PFV) and symptoms (CISS) were compared between those with and without accommodative dysfunction using analysis of variance and independent samples t-testing. Logistic regression was used to compare the effect of baseline accommodative function on treatment success [defined using a composite of improvements in: (1) clinical convergence measures and symptoms (NPC, PFV and CISS scores) or (2) solely convergence measures (NPC and PFV)]. RESULTS: Accommodative dysfunction was common in children with symptomatic CI (55% had decreased AA; 34% had decreased AF). NPC was significantly worse in those with decreased AA (mean difference = 6.1 cm; p < 0.001). Mean baseline CISS scores were slightly worse in children with coexisting accommodative dysfunction (decreased AA or AF) (30.2 points) than those with normal accommodation (26.9 points) (mean difference = 3.3 points; p < 0.001). Neither baseline accommodative function (p ≥ 0.12 for all) nor interaction of baseline accommodative function and treatment (p ≥ 0.50) were related to treatment success based on the two composite outcomes. CONCLUSIONS: A coexisting accommodative dysfunction in children with symptomatic CI is associated with worse NPC, but it does not impact the severity of symptoms in a clinically meaningful way. Concurrent accommodative dysfunction does not impact treatment response for CI.

Review: Head and Eye Movements and Gaze Tracking in Baseball Batting.

SIGNIFICANCE: After a 30-year gap, several studies on head and eye movements and gaze tracking in baseball batting have been performed in the last decade. These baseball studies may lead to training protocols for batting. Here we review these studies and compare the tracking behaviors with those in other sports.Baseball batters are often instructed to "keep your eye on the ball." Until recently, the evidence regarding whether batters follow this instruction and if there are benefits to following this instruction was limited. Baseball batting studies demonstrate that batters tend to move the head more than the eyes in the direction of the ball at least until a saccade occurs. Foveal gaze tracking is often maintained on the ball through the early portion of the pitch, so it can be said that baseball batters do keep the eyes on the ball. While batters place gaze at or near the point of bat-ball contact, the way this is accomplished varies. In some studies, foveal gaze tracking continues late in the pitch trajectory, whereas in other studies, anticipatory saccades occur. The relative advantages of these discrepant gaze strategies on perceptual processing and motor planning speed and accuracy are discussed, and other variables that may influence anticipatory saccades including the predictability of the pitch and the level of batter expertise are described. Further studies involving larger groups with different levels of expertise under game conditions are required to determine which gaze tracking strategies are most beneficial for baseball batting.

Results of a Prospective Dose Escalation Study of Linear Accelerator-Based Virtual Brachytherapy (BOOSTER) for Prostate Cancer; Virtual HDR Brachytherapy for Prostate Cancer.

PURPOSE: To demonstrate feasibility and toxicity of linear accelerator-based stereotactic radiation therapy boost (SBRT) for prostate cancer, mimicking a high-dose-rate brachytherapy boost. METHODS AND MATERIALS: A phase 1 sequential dose escalation study of SBRT compared 20 Gy, 22 Gy, and 24 Gy to the prostate and 25 Gy, 27.5 Gy, and 30 Gy to the gross tumor volume in 2 fractions, combined with 46 Gy in 23 fractions of external beam radiation. Feasibility of dose escalation (volume receiving 125% and 150% of the dose) while meeting organ-at-risk dose constraints, grade 2 acute and late gastrointestinal and genitourinary toxicity, and freedom from biochemical failure were secondary endpoints. RESULTS: Thirty-six men with intermediate- and high-risk prostate cancer were enrolled with a median follow-up of 24 months. Sixty-four percent of patients had high-risk features. Nine men were enrolled to dose level 1, 6 to level 2, and 6 to level 3. Another 15 patients were treated at dose level 3 on the continuation study. Dose level 3 achieved superior 125% (23.75 Gy) and 150% (28.5 Gy) dose compared to dose levels 1 and 2, with minimal differences in organ-at-risk doses. Kaplan-Meier estimate of freedom from biochemical failure at 3 years was 93.3%. There were no late grade 2 or 3 gastrointestinal events. The late grade 2 genitourinary toxicity at 2 years was 19.3%. Prostate-specific membrane antigen positron emission tomography was performed at 2 years with no local recurrences. CONCLUSIONS: We have shown that a linear accelerator-based SBRT boost for prostate cancer is feasible and can achieve doses comparable to high-dose-rate boost up to the 150% isodose volumes. Rectal, bladder, and urethral doses remained low, and long-term toxicity was the same as or better than previous reports from high-dose-rate or low-dose-rate boost protocols.

Post-therapy Functional Magnetic Resonance Imaging in Adults with Symptomatic Convergence Insufficiency.

SIGNIFICANCE: Prior studies have demonstrated the effectiveness of vergence-accommodative therapy in the treatment of convergence insufficiency (CI). These results show the changes in brain activation following therapy through the use of functional magnetic resonance imaging (fMRI). PURPOSE: The purpose of this study was to investigate changes in brain activation following office-based vergence-accommodative therapy versus placebo therapy for CI using the blood oxygenation level-dependent signal from fMRI. METHODS: Adults (n = 7, aged 18 to 30 years) with symptomatic CI were randomized to 12 weeks of vergence-accommodative therapy (n = 4) or placebo therapy (n = 3). Vergence eye movements were performed during baseline and outcome fMRI scans. RESULTS: Before therapy, activation (z score ≥ 2.3) was observed in the occipital lobe and areas of the brain devoted to attention, with the largest areas of activation found in the occipital lobe. After vergence-accommodative therapy, activation in the occipital lobe decreased in spatial extent but increased in the level of activation in the posterior, inferior portion of the occipital lobe. A new area of activation appeared in the regions of the lingual gyrus, which was not seen after placebo therapy. A significant decrease in activation was also observed in areas of the brain devoted to attention after vergence-accommodative therapy and to a lesser extent after placebo therapy. CONCLUSIONS: Observed activation pre-therapy consistent with top-down processing suggests that convergence requires conscious effort in symptomatic CI. Decreased activation in these areas after vergence-accommodative therapy was associated with improvements in clinical signs such as fusional vergence after vergence-accommodative therapy. The increase in blood oxygen level-dependent response in the occipital areas following vergence-accommodative therapy suggests that disparity processing for both depth and vergence may be enhanced following vergence-accommodative therapy.

Screening for convergence insufficiency in school-age children.

BACKGROUND: Convergence insufficiency (CI) is a common binocular vision disorder which often causes symptoms when doing near work. However, the best screening test for CI is unknown. The purpose of this study was to evaluate the ability of common tests of binocular and accommodative function to identify children with CI in a school screening setting. METHODS: Children aged nine to 14 were invited to participate. Positive fusional vergences, near point of convergence (NPC), accommodative amplitude, accommodative facility, Modified Thorington, and the Convergence Insufficiency Symptom Survey were evaluated. RESULTS: Of the 282 children tested, approximately 20 per cent had 2-3 signs of CI. One half of 2-3 signs of CI and 66 per cent of three signs of CI subjects were symptomatic. Approximately 61 per cent of subjects with symptomatic 2-3 signs of CI had an accompanying low accommodative amplitude. The largest area under the receiver operating characteristic curve was obtained using NPC break measurements. NPC break ≥ 6 cm for CI and NPC break ≥ 7 cm for symptomatic CI were the cut points that maximised the sum of sensitivity and specificity. CONCLUSION: NPC break performed best in identifying children with CI.

A review of proximal inputs to the near response.

Maddox proposed that the perceived nearness of a target could influence the ocular vergence response. Proximal inputs have been used to refer to all static and dynamic cues to depth other than disparity and blur. In this paper, we review a number of studies in which proximal influences have been assessed. While general agreement exists that proximal contributions are significant when blur and disparity cues are absent (open-loop conditions), there are conflicting reports on the role of proximal vergence and accommodation under closed-loop conditions.

Evaluation of single pixel step sizes in visual acuity assessment.

PURPOSE: Adaptive thresholding procedures (e.g., ZEST) benefit from testing near the current estimate of threshold. Therefore, small increments may improve precision of these techniques. We evaluated the validity of visual acuity assessment when letters are not constrained to a multiple of 5 pixels high. METHODS: Snellen letters were presented over a ±5 pixel range spanning the final threshold estimate. Sizes that were a multiple of 5 pixels (e.g., 20 and 25) were presented 160 times, and other sizes were presented 40 times. This resulted in 320 letter presentations at multiples of 5 and at non-multiples of 5. Post hoc ZEST procedures were used to compute acuity threshold estimates based on testing at those two sets of sizes. Two subjects participated: subject 1 for the right and left eyes and subject 2 in two sessions with binocular viewing. Psychometric functions were fit to the data and were used to model simulated observers. Simulations were run for each data set, and the number of presentations at each size matched the number presented to the subject. Ninety percent limits for proportion correct at each letter size were determined from the simulation data, and these limits were used as criteria for identifying outliers in the subject's data. RESULTS: No significant difference in acuity thresholds were found when letters were rendered in multiples of 5 pixel heights vs. letters without this constraint. Empirical data fell within the bounds defined by simulations, with no idiosyncratic results found for either set of letter sizes. CONCLUSIONS: Letter sizes that do not conform to a multiple of 5 pixel letter height yield valid acuity scores. This facilitates adaptive psychometric procedures for acuity testing, such as ZEST and QUEST, in which letter sizes are selected to be as close to the current estimate of threshold size as possible.

Effectiveness of placebo therapy for maintaining masking in a clinical trial of vergence/accommodative therapy.

PURPOSE: To evaluate the effectiveness of the Convergence Insufficiency Treatment Trial (CITT) placebo therapy program in maintaining masking of patients randomized to the office-based treatment arms, determine whether demographic variables affect masking, and determine whether perception of assigned treatment group was associated with treatment outcome or adherence to treatment. METHODS: Patients (n = 221, ages, 9-17 years) were randomized to one of four treatment groups, two of which were office-based and masked to treatment (n = 114). The placebo therapy program was designed to appear to be real vergence/accommodative therapy, without stimulating vergence, accommodation, or fine saccades (beyond levels of daily visual activities). After treatment, patients in the office-based groups were asked whether they thought they had received real or placebo therapy and how confident they were in their answers. RESULTS: Ninety-three percent of patients assigned to real therapy and 85% assigned to placebo therapy thought they were in the real therapy group (P = 0.17). No significant differences were found between the two groups in adherence to the therapy (P >or= 0.22 for all comparisons). The percentage of patients who thought they were assigned to real therapy did not differ by age, sex, race, or ethnicity (P > 0.30 for all comparisons). No association was found between patients' perception of group assignment and symptoms or signs at outcome (P >or= 0.38 for all comparisons). CONCLUSIONS: The CITT placebo therapy program was effective in maintaining patient masking in this study and therefore may have potential for use in future clinical trials using vergence/accommodative therapy. Masking was not affected by demographic variables. Perception of group assignment was not related to symptoms or signs at outcome (ClinicalTrials.gov number, NCT00338611).

The forced vergence cover test and phoria adaptation.

Phoria adaptation (PA) provides innervation to help maintain the correct vergence posture for binocularly viewing objects. Once fusion is disrupted, such as is required for measuring a (dissociated) phoria, this innervation is slowly depleted. Thus, extended periods of monocular occlusion can be required to dissipate PA and reveal the full extent of the phoria. Two versions of a forced vergence modification of the alternating cover test (CT) have been proposed to rapidly show the full phoria. We evaluated the ability of these forced vergence CTs (FVCT-1 and FVCT-2) to deplete the PA induced by a 15 min adaptation period to base out prism. In both experiments, the CT followed by the FVCT was performed before and after the adaptation period. In Experiment 1 (n = 13), the FVCT-1 was evaluated at 40 cm. Experiment 2 (n = 32) evaluated the FVCT-2 at 4 m. In Experiments 1 and 2, the difference between pre- and post-adaptation CTs showed significant PA occurred during the adaptation period (7.8(Delta), p < 0.0005, and 5.4(Delta), p < 0.0005 respectively). In Experiment 1, the FVCT-1 did not reveal a larger phoria than the CT before (mean difference: 0.4(Delta), p = 0.34) or after (no difference for all subjects) the adaptation period. Thus, the FVCT-1 did not alter PA. In Experiment 2, the FVCT-2 did show a shift in the phoria compared to the CT. However, this shift was found to be equivalent before and after the adaptation period (mean difference in shift: 0.22(Delta), 95% CI: -0.52 to 0.96(Delta)). Thus, the FVCT-2 shifts the phoria a constant amount independent of the amount of PA present. We conclude that neither FVCT's behaviour is dependent on the PA present. Thus, these procedures are unlikely to be effective clinical procedures for revealing the full magnitude of the phoria.